1. Field of the Invention
The present invention relates to a semiconductor device including a pixel electrode, and particularly to a display device. More particularly, the present invention relates to a semi-transmission type liquid crystal display device including a reflection region and a transmission region.
2. Description of the Related Art
A display device is divided into a self-light emitting display device and a non-light emitting display device. A liquid crystal display device is the most typical non-light emitting display device. In general, a liquid crystal display device performs a display by being irradiated with light from a backlight because it does not emit light.
In a transmission type liquid crystal display device which uses light from a backlight, although a display image is easy to see in a normal room, there is a problem that a display image is difficult to see under sunlight. Particularly electronic apparatuses which are frequently utilized outdoors such as a camera, a portable information terminal, and a mobile phone are greatly affected by this problem.
A semi-transmission type liquid crystal display device has been developed in order to display a favorable image both indoors and outdoors. A semi-transmission type liquid crystal display device includes a reflection region and a transmission region in one pixel. The transmission region includes a transparent electrode and transmits light so as to function as a transmission type liquid crystal display device. On the other hand, the reflection region includes a reflective electrode and reflects light so as to function as a reflection type liquid crystal display device. In this manner, a clear image can be displayed both indoors and outdoors.
As such a liquid crystal display device, there are a passive matrix type and an active matrix type. Generally, when manufacturing an active matrix type display device, a wiring which is connected to a semiconductor layer of a thin film transistor (TFT) is formed and a conductive film functioning as a pixel electrode is formed over the wiring.
As a pixel electrode, there are a reflective electrode in a reflection region and a transparent electrode in a transmission region. Each electrode has a different shape. Therefore, a resist mask for forming a reflective electrode and a resist mask for forming a transparent electrode have been required (for example, refer to Patent Documents 1 to 5).
[Patent Document 1]
Japanese Published Patent Application No. 2002-229016
[Patent Document 2]
Japanese Published Patent Application No. 2004-46223
[Patent Document 3]
Japanese Published Patent Application No. 2005-338829
[Patent Document 4]
Japanese Published Patent Application No. 2004-334205
[Patent Document 5]
Japanese Published Patent Application No. 2004-109797